docs: organize test index into categories #5829

Job	Run time
check_format_and_unit_tests	1m 6s
build / Special integration tests (17)	2m 40s
build / Special integration tests (25)	2m 43s
build / Special integration tests (21)	2m 34s
build / httpclient-tests (jdk) / Integration tests (25, 1.32.0, jdk)	23m 38s
build / httpclient-tests (vertx) / Integration tests (25, 1.32.0, vertx)	22m 29s
build / httpclient-tests (jetty) / Integration tests (25, 1.32.0, jetty)	23m 18s
build / integration_tests (25, 1.31.8) / Integration tests (25, 1.31.8, vertx)	23m 45s
build / integration_tests (25, 1.32.4) / Integration tests (25, 1.32.4, vertx)	23m 6s
build / integration_tests (21, 1.31.8) / Integration tests (21, 1.31.8, vertx)	24m 15s
build / integration_tests (25, 1.33.1) / Integration tests (25, 1.33.1, vertx)	24m 5s
build / integration_tests (17, 1.33.1) / Integration tests (17, 1.33.1, vertx)	24m 33s
build / integration_tests (17, 1.32.4) / Integration tests (17, 1.32.4, vertx)	23m 46s
build / integration_tests (17, 1.30.12) / Integration tests (17, 1.30.12, vertx)	22m 0s
build / integration_tests (21, 1.32.4) / Integration tests (21, 1.32.4, vertx)	23m 41s
build / integration_tests (21, 1.30.12) / Integration tests (21, 1.30.12, vertx)	23m 7s
build / integration_tests (21, 1.33.1) / Integration tests (21, 1.33.1, vertx)	24m 26s
build / integration_tests (25, 1.30.12) / Integration tests (25, 1.30.12, vertx)	23m 3s
build / integration_tests (17, 1.31.8) / Integration tests (17, 1.31.8, vertx)	24m 12s
	6h 2m 27s

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